RW: Mighty Guard (VIII)
Kill order: Fire > Ice > Thunder
1st turn: Tyro: SG, Rydia: Ruinga, Cloud: Fenrir Overdrive, Rinoa: Mighty Guard, Y'shtola: Slowga @Ice.
2nd turn: Tyro: Blindga @Thunder, Rydia Ruinga (repeat until Fire dies), Cloud: Blizzara Strike (until Fire dies), Y'shtola: Slowga @Fire.
After this;
Tyro: Magic Breakdown @Fire>Ice>Thunder. Blindga remained on Thunder almost until the end. It can rarely cast Esuna, so look out to reapply asap.
Rydia: Switch to Firaja @Ice obviously when Fire is dead. I ran out of abilities when Thunder was the only one left so had to use Shiva SB twice.
Cloud: He had some Blizzara Strike left to use on Thunder but didn't need them since I had Quad Cut available most of the time. It was doing 2250~ish damage/hit on Thunder and did more damage than Blizzara Strike (no weakness, no 9999). Lifesiphon when needed obviously.
Rinoa: She had some Blizzaja left to use on Thunder, but I used up Bioga first. Her aoe earth/slow SB sucked.
Y'shtola: I only needed to recast Slowga once @Ice and used Medica II once. She died near the end due to an unlucky Electrocute attack.
The main problem I had was running out of Magic Breakdowns a little past half way through Thunder and its thunder attacks started hitting like a truck. I couldn't pull off another SG so that last part was pretty painful. Until then it goes pretty smooth once mitigations are on at start.